Almost 20% of young adults (18-39 years old) in the United States have hypertension; yet, hypertension is under-recognized as a cardiovascular risk factor in young adults. This proposal will address the serious problem that only one-third of hypertensive young adults have their hypertension controlled (35%), compared to 51% of middle-aged and 48% of older adults. However, once blood pressure medication is initiated after appropriate lifestyle intervention, young adults achieve the highest hypertension control rates (70%), suggesting barriers in assigning a diagnosis and initiating medication in young adults. The primary factors driving delays in the diagnosis and treatment in young adults are unknown. Thus, it is unknown what the optimal interventions are to improve hypertension control in young adults. As an academic preventive cardiologist, Dr. Johnson's goal is to lead an independent translational research program to improve guideline implementation and hypertension control in young adults. This 5-year proposal will advance her career goals by providing the necessary support and training in complex intervention development and implementation. Dr. Johnson is well prepared to successfully complete this proposal. With focused training, expert mentorship, and a novel research plan, she will transition to an independent investigator with R01 support and an established research program in cardiovascular disease prevention for young adults. The proposed aims are to: 1) determine provider, system, and patient factors explaining delays in assigning a diagnosis of hypertension in young adults, 2) determine provider, system, and patient factors explaining delays in the initiation of hypertensive treatment in young adults, and 3) design an intervention to reduce delays in the diagnosis of hypertension and initiation of antihypertensive medication in young adults. Aims 1 and 2 apply a model of clinical inertia to evaluate barriers to hypertension control in young adults. Electronic health record data from a large physician group will be extracted for 8,385 patients and 325 primary care providers. A survey of these primary care providers will assess knowledge, attitudes, and perceived barriers. Aim 3 uses an established technique of intervention mapping; identified barriers to hypertension management in young adults will be mapped to an intervention and assessed with focus groups of providers, patients, and administrators. This proposal directly responds to NHLBI's goals of developing system-oriented approaches to increase evidence-based guideline use and developing interventions to improve system performance and health outcomes.